This paper argues for the following finiteness universal: an infinitive cannot co-occur with a high complementizer (such as "that" in English). Although such an observation may seem trivial, assuming Rizzi (1997)’s articulated CP allows one to redefine "that." In a vein similar to Wurmbrand and Lohninger (2019), I propose that infinitives can come in different sizes. This paper combines Pesetsky (2021)’s arguments that finiteness is a matter of clause size together with truncation theories of infinitives such as Shlonsky and Soare (2011)’s to argue for a novel understanding of finiteness, proposing precise and falsifiable definitions for finite and nonfinite clauses. Based on a crosslinguistic survey of several different languages belonging to many different language families, I present a theory of finiteness under which a clause is defined as nonfinite iff its ForceP/CP2 layer has been truncated, and finite iff it is untruncated. Although derivational theories of finiteness predict this generalization, infinitives come in at least seven different sizes crosslinguistically. Beyond arguing for this finiteness universal, this paper also discusses the cartographic predictions that result from maximal size of infinitives in a given language.